1 Gemfilte

gem 'lazybox'

2 application.css

*= require lazybox

3 application.js

//= require lazybox

4 application.js

$.rails.allowAction = $.lazybox.confirm;

And we are Done

add classes to links to apply your style:

$.lazybox.settings = {cancelClass: "button gray", submitClass: 'button gray', overlay: false}

Lazybox Gem Documentation